Light valve assembly for motion picture film printer



350 27 1 SEARCH Room July s, 1969 w G, ENGEL 3,454,328

LIGHT VALVE ASSEMBLY FOR MOTION PICTURE FILM PRINTER Filed Jan. 19, 1966fig.

32 (PR/on ART) /D'EMSITY United States Patent O 3,454,328 LIGHT VALVEASSEMBLY FOR MOTION PICTURE FILM PRINTER Willi G. Engel, Evanston, Ill.,assignor to Bell & Howell Company, Chicago, Ill., a corporation ofIllinois Filed Jan. 19, 1966, Ser. No. 521,580 Int. Cl. G02f 1/30; G03b9/08, 27/02 U.S. Cl. 350-271 3 Claims ABSTRACT OF THE DISCLOSURE Theadjusted position of the vanes of a light shutter are controlled by theangular condition of a roller which is displaceable into lockedcondition against a bearing defined by the edge of a cup from which theroller is extendable. The cup is adjustable to adjust the position ofroller locking means in the bearing. Resiliently padded springs in thecup prevent vane fiutter d-ue to bounce upon engagement of the rollerwith the bearing and the locking means.

The present invention relates to photographic printers. Particularly theinvention relates to light valve apparatus for film printers.Specifically, the invention relates to control means for light vanes ofa light valve apparatus of a motion picture film printer and the like.

The employment of vlight vanes or shutters in film printing, toadjustably control the cross-sectional area of light from a source tothe end that therefrom resulting intensity and/or color composition ofprinting light is adjusted to compensate for varying lighting conditionsunder which themes being printed were originally exposed, is well knownin the art. One heretofore known mechanism for controlling vanes of theclass described comprises a cup which is rotated through a synchronizingmechanism in response to desired changes in light intensity. The cup hasan edge fashioned with a pair of diametrically disposed V-shapedrecesses the angular positions of which are synchronized with vanespacing. To releasably adjust and lock the vanes in adjusted positions aroller assembly comprising diametrically opposed rollers is guided intonadirs of the angles of said recesses by being forcibly drawn againstthe edge of the cup. The roller assembly is operably connected to anassembly of the vanes and as it is motivated toward the nadirs in whichits rollers become releasably locked, it adjusts the vanes.

The kinetic energy generated by the force with which the rollerassemblies of prior printers are drawn into their operating positionscause them to bounce against their respective cup edges. That phenomenonproduces undesirable effects in a film being printed because ofvariations in the light volume passed from between the shutters as theyvibrate in response to roller assembly bounce.

It is an object of the present invention to provide improved light valvemeans in a film printer and the like for adjusting the volume ofprinting light.

It is a further object of the present invention that said light valvemeans comprise a pair of cooperatively arranged vanes and an improvedcontrol mechanism therefor.

It is another object of the present invention that said controlmechanism include a cup-like member having an edge fashioned withV-shaped recess means into which a vane controlling roller assembly isforcefully drawn to adjust the vanes by edge motivation of said rollerassembly and cushioning means for absorbing the impact of the rollerassembly with said cup-like member.

An additional object of the invention is that said cushioning means beof impact absorbing fabrication and Patented July 8, 1969 arranged inthe walls of said cup-like member adjacent the edge thereof whereby theroller assembly is precluded from bouncing as it is forcefully drawninto the recess means.

The foregoing and other objects, features and advantages of the presentinvention will become more apparent upon consideration of the followingdescription and appended claims, when considered in conjunction with theaccompanying drawings wherein the same reference character 0r numeralrefers to like or corresponding parts throughout the several views.

On the drawings:

FIG. 1 is a schematic view in perspective of a light valve assembly fora film printer and embodying the present invention.

FIG. 2 is an end view of the cuplike member and roller assembly of thelight valve assembly, portions of lthe latter having been omitted, andportions being broken away for the purpose of illustration.

FIG. 3 is an elevational view looking toward the right of FIG. 2.

FIG. 4 is an enlarged view schematically illustrating the relationshipof the cup-like member and roller assembly during vane adjustment.

FIG. 5 is a graphic comparison of the density vs. film length curvesrepresenting the paths of a pair of vanes actuated by a prior art vanecontrol mechanism and my improved vane control mechanism. y

Referring now more particularly to the drawings, in FIG. 1 aphotographic printer generally designated 10 is employed forcontinuously exposing raw film stock 11 by means of light rays passingthrough a printed processed film 12 having segments depicting sceneswhich may have been exposed under varying lighting conditions. To theend that related scenes when printed will appear as having been exposedin natural relationship rather .than disjointedly, known means areprovided for variably obscuring the cross-sectional area of the beamwith light valve mechanisms. With these mechanisms, the brightness ofthe beam is varied.

Although the invention is described as it relates to a single lightbeam, a printer capable of printing color is understood to have a lightvalve assembly associated with each chromatic beam into which a -beam ofwhite light is split. Each light valve assembly varies its beam beforethat chromatic beam is recombined into a white beam having compensatedchromatic values, by which film 11 is exposed through the film 12.Inasmuch as illustrating a plurality of light valve assemblies addsnothing -to the understanding of the invention, they have been omittedfrom the drawings.

The beam affected by the light valve apparatus shown in FIG. 1 is passedalong an optical axis 14 through a conventional relay lens 13. The beamthen passes through an adjustable vane slot 16 toward the film strips 11and 12. The slot 16 is defined by a pair of conventional adjustablelight vanes or shutters 15 and 85 which are adapted to vary thecross-sectional area of a beam passing about the axis 14. Each of .thevanes 15 and 85 is secured along an outer edge on an axis pin (notshown) which is journalled in a respective of suitably mounted cylinders17 and 87. A pair of pinions 18 and 88 are constrained for rotation onthe axis pins of the vanes 15 and 85 for control thereof in a mannerhereinafter to be described.

A cup-like member which may be referred to as a solenoid cup 19 isdefined by a wall 89 of cylindrical configuration. At its vane proximateend said wall comprises a bearing defined by rim or edge 20 which isfashioned with a pair of diametrically opposed broad V-shaped recesses21 and adapted for. bearing support of a roller assembly generallydesignated 22.

The roller assembly 22 comprises a medial body 23 disposed normally tothe axis about which the solenoid cup is generated. From the oppositeends of said roller assembly body 23 there projects outwardly a pair ofdiametrically aligned pins 24 which extend over diametrically oppositeportions of the edge 20. A pair of rollers 25 are rotatably arranged onthe pins 24, respectively. The roller assembly body 23 is adapted forrocking about a fixed axis of rotation provided by a shaft 27 with whichsaid body is constrained for movement. Said shaft projects through theopposite end 26 of the cup in which said shaft not only is journalledbut also is reciprocative longitudinally thereof to move the rollerassembly 22 toward and away from the edge 20, that is, to the right andleft relative to FIG. 3 and thereby comprises means for moving roller 25into and out of engagement with edge 20. Reciprocation of the shaft 27to the right may be achieved by a solenoid (not shown) which operatessaid shaft and is capable of exerting 40 pounds of pull against theroller assembly to condition it into engagement with the edge 20. Acoiled spring 28 is positioned between the cup 19 and roller assembly 22in surrounding relationship with shaft 27. Spring 28 normally urges theshaft 27 and rollers 25 to the left in FIG. 3 so that the rollers areout of engagement with rim or edge 20.

Rotational movement of the assembly 22 causes adjustment of the vanesand 85. For that purpose, a gear sector 30 which is constrained forrotation with the shaft 27 meshes with the pinion 18 to drive itsassociated vane 15, as illustrated in FIG. 1. The gear sector 30 alsooperably meshes with a suitably supported gear sector 31 for driving theother of the pinions 88 to rock its associated vane 85. Accordingly, asthe gear sector 30 moves counterclockwise from the position shown inFIG. 1, the vanes will move toward the dotted line position shown inFIG. 1 and slot 16 will enlarge. Contrariwise, upon opposite rotation ofthe gear sector 30 said vanes 4will move to narrow said slot.

By heretofore known light responsive means (not shown), when adjustmentof the vanes is required, the roller assembly 22 will be disengaged fromthe edge 20 by outward extension of shaft 27. Simultaneously, the cup19, the angular position of which is synchronized to provide vaneadjustments required, will be rotated about the axis defined by shaft 27to set the nadirs of the angles formed by the recesses 21 in a positionsuch that when the rollers 25 are engaged against edge 21 in such nadirsthe vanes will have lbecome arranged to allow passage of only thedisired Volume of light through the slot 16. v 5

In FIG. 4, the relative positions of the solenoid cup y19 and the rollerassembly 22 during vane adjustment is illustrated diagrammatically. Theoperative position of the roller assembly immediately prior to releaseor disengagement from edge for adjustment is shown in solid lines anddesignated A. By reason of the proportioning of the parts, the rollerassembly is locked in the recesses 21 when disposed in the A position.When the requirement for adjustment arises the roller assembly isextended from cup 19 by heretofore known means and assumes the dottedline B position. Simultaneously, by heretofore known means the cup 19 isrotatedto the cup position shown in dotted lines in FIG. 4. The lattercup position is synchronized to produce desi-red Ivane conditioning.Thereafter, by heretofore known means which include a solenoid to whichreference was previously made herein, the shaft 27 is drawn inwardly toengage the roller assembly xwith the edge 20 of the adjusted cup atdiametrically opposed positions designated C which are then removed fromthe nadirs of the angles of the recesses 21 Ibecause of the priorrotation of said cup. The inward force with which the roller assembly isdrawn causes it to rotate about the axis of shaft 27 and thereby slidethe Yrollers 22 into the nadirs of angles of the recesses 21 to thedotted line position designated D in FIG. 4 as the roller assembly iscammed by the sloping sides of the recesses 21 which define means fordisplacing rollers 25 along edge 20. As the roller assembly rotates tothe D position, the vanes become adjusted, the roller assembly beinglocked in adjusted position when said rollers become seated in saidnadirs.

The cup 19 is rotatable in both directions of rotation depending uponlight volume requirements. Consequently, the roller assembly 22 isadapted to rotate in opposite angular directions depending upon therelative positions of recesses 21. Accordingly, the vanes areautomatically adjustable to either enlarge or yreduce the light passingslot 16.

The force with which the roller assembly is drawn against the edge 20 toadjust the vanes is of a magnitude sufficient to cause said rollerassembly to bounce if a prior solenoid cup is employed in printer 10.The vane path, in such event, would `be as illustrated graphically at 32in FIG. 5 through a graph based on a film density vs. film length curve.Ensuing light volume variations could ca'use undesirable apparentvariation of intensity values in the film 11. By employing the presentimprovement, the bounce evident with prior constructions as seen in thecross-hatched area under curve 32, is eliminated and vane adjustmentwill be in a substantially straight or uniform path as graphicallyillustrated at 33 in FIG. 5.

For efectuating the improved result, a shock absorbing mechanism isprovided. lt comprises a plurality of elastomer pads 34 which arearranged in the walls 89 of the cup inwardly from the edge 20. In thepresent embodiment, each pad 34 is engaged in a slot 35 which is formedadjacent and parallel the edge of each leg of each V configurationdefining a recess 21. Accordingly, the slots 35 are associated in pairs,one thereof for each recess 21. Shock absorption is augmented by partingthe wall 89 inwardly from edge 21 at the nadirs of the angles formingeach recess to connect each associated pair of slots 35 through a neckspace 36. Such arrangement generates a pair of resilient fingers 37which define each of the recesses 21 and serve to retain associatedelastomer pads 34. To additionally facilitate retention of the saidpads, the adjacent ends of each pair of slots 35 are restricted by anintegral wall section or boss 38 as illustrated in FIGS. 3 and 4.However, the bosses 38 do not entirely separate associated slots, theadjoining ends of which communicate through narrows 39 which arecommunicatively connected to the neck space 36.

As many substitutions or changes could be made in the above-describedconstruction and as many apparently widely different embodiments of theinvention 'within the scope of the claims could be constructed withoutdeparting from the scope and spirit thereof, it is intended that allmatter contained in the accompanying specification shall be interpretedas being illustrative and not in a' limiting sense.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1.v A device of the type having a light valve including adjustable vanemeans defining a variably dimensioned light passing slot for controllingthe cross-sectional area of a beam of light to which a stream of film isto be exposed, and comprising:

an elongated bearing mounted for adjustment to control the dimensions ofsaid slot;

a roller arranged for movement between an extended condition in whichsaid roller is spaced from said bearing during adjustment therof and anengaged condition in which said roller is displaceable along saidbearing;

locking means fashioned for limitingdisplacement of said roller alongsaid bearing when in engaged condition; coupling means connected to saidvane means for adjusting the dimension of said slot as said roller isdisplaced; means for moving the roller into and out of engagement withsaid bearing; means for displacing said roller along said bearing,

when in engaged condition; and resilient means for absorbing shockgenerated when said roller is moved into engagement with and displacedalong said bearing toward said locking means. 2. A device according toclaim 1 characterized by a cup having yan edge comprising said bearing,said edge having a pair of opposed recesses defining said locking means,said recesses being proportioned to prevent angular displacement of saidroller to secure said vane means in adjusted positions, the resilientmeans arranged in the wall of the cup and extending longitudinally ofsaid edge. 3. A devive according to claim 2 characterized in that aplurality of spring-like fingers are fashioned in said cup, said cuphaving a plurality of slots which together with said edge define saidfingers, the resilient means comprised of pad-like structures held insaid slots for .absorbing force of impact of said roller against saidRONALD L. WIBERT, Primary Examiner.

ORVILLE B. CHEW II, Asirstant Examiner.

U.S. C1. X.R'.

